1. Technical Field
The present invention relates generally to processing wafers, and more particularly relates to a method for treating an edge portion of a wafer with a plasma or select chemical formulation in order to enhance adhesion characteristics and inhibit delamination of a layer of material from the wafer surface or to clean the wafer surface only on the edge portion that is being treated.
2. Related Art
Delamination is a major problem for the integration of interconnect structures for integrated circuits. Delamination occurs during chemical-mechanical polishing (CMP) of layered stacks of films, and is due to the inherently poor mechanical qualities of the materials used. The problem is especially prevalent in the edge region of the wafer since the induced stress during CMP is highest in regions of great surface topology.
Prior art treatments to prevent delamination treat the entire wafer area. These treatments cause the surface of the treated material to densify, thus hardening the surface, and are accompanied by compositional changes of material. While addressing the issue of delamination, these whole-wafer treatments cause unacceptable new problems, including: uncontrolled change in the composition chemistry of the treated material, moisture uptake after the treatment, increases in the relative permeability of the dielectric materials, and the introduction of a new interface inside the treated material between the densified surface and the untreated bulk.
U.S. Pat. No. 6,642,128, “Method for High Temperature Oxidations to Prevent Oxide Edge Peeling,” issued to Lu et al. on Nov. 4, 2003, which is hereby incorporated by reference, teaches a method for preventing oxide peeling by applying a silicon nitride layer to a backside of a wafer prior to carrying out high temperature annealing. Unfortunately, the teachings are limited to, inter alia, batch processing, require the presence of a silicon nitride film, and the processing according to the teaching impacts the entire wafer surface.
Accordingly, a need exists for an improved method for preventing delamination that occurs during CMP.